Landscape Rock Calculator
Landscape rock, pebbles and decorative stone: work out the volume and weight for your beds, plus bags or bulk tons, with an editable density.
Landscape rock covers decorative stone of every kind: pebbles, cobbles, crushed granite, marble chips and slate. It's sold by the bag at garden centres and by the ton, tonne or yard from landscape suppliers. Enter the size of each bed and the depth, and this calculator gives the volume in cubic yards or m³, the weight in tons or tonnes, and the bags you need. It starts at a typical 1.5 tonnes per m³ for decorative stone, and you can change that to your supplier's figure. Lava rock and other light stone weigh far less than dense rock, so their density makes a big difference to the tonnage.
- Volume
- 1.17 yd³
- Weight
- 1.47 tons
- Bags
- 63
31.5 ft³ · 0.892 m³
2,940 lb · 1.33 tonnes
0.5 ft³ bag
| 0.5 ft³ bag | 63 |
|---|---|
| 25 kg bag | 54 |
| 20 kg bag | 67 |
| 850 kg bulk bag | 2 |
How it was worked out
- Area: 12 ft × 10 ft = 120 ft²; × 3 in (0.25 ft) deep = 30 ft³
- 30 ft³ ÷ 27 = 1.11 yd³
- Plus 5% extra = 1.17 yd³
- 1.17 yd³ × 1.26 tons per yd³ = 1.47 tons (2,940 lb)
- 31.5 ft³ ÷ 0.5 ft³ per bag = 63, rounded up to 63 bags
Typical weights of common materials
| Material | t/m³ | tons/yd³ | lb/ft³ |
|---|---|---|---|
| Concrete | 2.40 | 2.02 | 150 |
| Gravel | 1.60 | 1.35 | 100 |
| Pea gravel | 1.60 | 1.35 | 100 |
| Crushed stone / crushed rock | 1.60 | 1.35 | 100 |
| River rock | 1.50 | 1.26 | 94 |
| Landscape rock / pebbles | 1.50 | 1.26 | 94 |
| Crushed limestone | 1.60 | 1.35 | 100 |
| Decomposed granite | 1.50 | 1.26 | 94 |
| Crusher run | 1.60 | 1.35 | 100 |
| Road base | 1.70 | 1.43 | 106 |
| Crusher dust | 1.50 | 1.26 | 94 |
| Aggregate (20 mm) | 1.60 | 1.35 | 100 |
| All-in ballast | 1.65 | 1.39 | 103 |
| MOT Type 1 sub-base | 1.80 | 1.52 | 112 |
| Sand | 1.60 | 1.35 | 100 |
| Topsoil | 1.30 | 1.10 | 81 |
| Garden soil | 1.30 | 1.10 | 81 |
| Fill dirt | 1.40 | 1.18 | 87 |
| Mulch | 0.35 | 0.29 | 22 |
| Bark chippings | 0.30 | 0.25 | 19 |
| Asphalt (compacted) | 2.32 | 1.96 | 145 |
Loose, as-delivered figures; asphalt and concrete are as laid. Moisture, stone size and source change the real weight, so use your supplier's figure when you have it. Tons are US short tons (2,000 lb).
Common use cases
- Decorative stone for beds, borders and around trees
- Xeriscape and gravel gardens that need little water
- Rock mulch around plants instead of bark
- Comparing the cost of bags with a bulk load
How to use
- Choose feet and inches or metres and millimetres, and the country whose bag sizes you want.
- Enter the length and width of the area, or switch the shape to a circle, triangle or a known area. Use Add another area for L-shapes and separate beds.
- Enter the depth of rock. Decorative stone is often laid 2 to 3 inches (50 to 75 mm) deep over landscape fabric.
- Check the density and the extra allowance. Change the density if your supplier quotes a different figure.
- Read the volume, weight and bag count, and add a price per ton, cubic yard, m³ or bag for a cost estimate.
FAQ
How much landscape rock do I need?
Multiply the area by the depth: 100 ft² at 2 inches is 16.7 ft³, about 0.62 cubic yards, and roughly 0.8 US tons at a typical density. Add a little extra for uneven ground.
Is rock heavier than mulch?
Much heavier: a cubic yard of rock can weigh well over a ton, while a cubic yard of wood mulch weighs a few hundred pounds. Check what your vehicle or trailer can carry before collecting it.
What about lava rock?
Lava rock is porous and much lighter than solid stone. Enter the density your supplier gives (or the weight of one bag and its volume) to get a realistic tonnage.
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